A gold-bearing arsenic concentrate from Inner Mongolia is a typical refractory gold ore, where gold exists in an encapsulated form within arsenopyrite (FeAsS) and pyrite (FeS2). The encapsulation of arsenides not only severely reduces the efficiency of cyanide leaching of gold extraction but also affects environment. The method of removing arsenic and extracting gold by pressurized oxidation was studied. The influences of sulfuric acid concentration, oxygen partial pressure, reaction temperature, solid mass to liquid volume ratio, and reaction time on the leaching effect were investigated. The process conditions were optimized and the key constraints were revealed. The results show that pressure leaching can effectively destroy the coating structure of gold by sulfides and arsenides, and there is no emission of harmful gases such as As2O3 and SO2 throughout the process. Its environmental friendliness is significantly better than that of oxidation roasting. The optimal process conditions are determined as follows:sulfuric acid concentration of 0.4 mol/L, oxygen partial pressure of 1.5 MPa, reaction temperature of 160 ℃, solid mass to liquid volume ratio of 1∶100, and leaching time of 120 min. Under the conditions, the arsenic leaching rate reaches 96%, and the mass fraction of gold in the leaching residue is 28 g/t, which is significant increased compared with 4.5 g/t of the raw ore. The persistent presence of ferric arsenate (FeAsO4) precipitate in the leaching residue is the core factor restricting the complete removal of arsenic and the further improvement of gold grade. The research results can provide technical references for the clean and efficient utilization of similar refractory gold mines.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |